Variable pitch airscrew



P. P. RATEE VARIABLE PITCH A IRSCREW 2 Sheets-Sheet 1 Filed Nov. 5, 1936 INVENTOR PIERRE PAUL RATIE ATTORNEYS Jan. 16; 1940. RF. RATIE VARIABLE PITCH AIRSCREW Filed Nov. 5'; 1936 2 Sheets-Sheet 2 Q%ZW; ATTORNEYS INVENTOR PIERRE PAUL RATIE [BY 42am Patented Jan. 16, 1940 UNITED STATES PATENT OFFICE- VARIABLE PITCH AIRSCREW Application November 5, 1936, Serial No. 109,318 In France April 1, 1936 1 Claim.

This invention relates to a' variable pitch airscrew the change of pitch of which is controlled by a motor, for instance an electric motor, and

is automatically determined by the variations of 5 the speed of rotation of the airscrew.

The said variable pitch airscrew according to the invention is then in the form of a combination of a variable pitch airscrew, of a motor for modifying the pitch, of a tachometer or the like, and of a switching system, placed under the control of the tachometer, for controlling in its turn the operation of the motor modifying the pitch.

The switching system is so devised that, when the number of revolutions per minute of the motor exceeds a certain value, the airscrew is moved towards the highest pitch position, and so that, when the number of revolutions falls below another value (smaller than the preceding one), the airscrew is moved towards the lowest pitch position. These two values and their diiference must preferably be adjustable at the pilots desure.

The contacts or the-like, controlled by the tachometer and which ensure the closing of the circuits for causing the motor to rotate in one direction or the other, in order to move the blades towards the lower pitch or higher pitch positions, can be adjusted in position, and said adjustment can be automatically effected by the position of the throttle control lever.

The installation comprises a four-position control switch, which positions respectively correspond: the first to the opening of the various 35 circuits, the second to the operation under the control of the regulator such as a tachometer, the j- 7 third and the fourth to the closing of the circuits for moving the blades towards the higher pitch and lower pitch positions.

The accompanying drawings illustrate, by way of example only, forms of carrying the invention into practice.

Fig. 1 is a diagrammatic view of a first form of construction.

Fig. 2 is a diagrammatic perspective view of the regulator of Fig. 1.

Fig. 3 is a diagrammatic view of a second form of construction.

In the drawings, the blades of the airscrew have not been illustrated. The tachometer (or similar instrument) has only been shown in a purely diagrammatic manner because the constitution of the tachometer does not concern the features of the present invention. It is to be understood that by the term tachometer is meant any device measuring or indicating the speed of rotation of the engine.

In the example illustrated in Figs. 1 and 2, the tachometer is represented by a pointer or index I which moves opposite a dial 2. The pointer is connected (see Fig. 2),, through the medium of a wire and of a brush I to a conducting drum l on which also rubs a brush I Contacts 5 and 6 for respectively controlling the lower pitch and higher pitchare respectively connected to conducting drums 5 and B for contact 5, by a Wire 8| and a brush 5, and, for contact 6, by a wire 82 and a brush 6. Two brushes 5 and 6 rub on the conducting drums 5 and 6 The unit, constituted by the contacts 5, 6 and drums 5*, l 6 is arranged on a tubular shaft surrounding the shaft of the index I, and can be adjusted in position through the medium of an arm 84 fixed on the tubular shaft; on said arm 84 is fixed a finger 83 entering an arcuate opening 85 provided in the dial 2. The arm 84 can be moved by the pilot, or its displacement can be directly efiected, as shown in Fig. 1 through the medium of the throttle control lever 86. For that purpose, the arm 84 and the throttle control lever 86 are connected by a link 81 carrying a contact piece 88 capable of engaging, in throttle opening position, between the contacts 89 and 90.

The installation comprises a series motor 1 having two field windings 8 and 9 and thus capa ble of rotating in both directions according as winding 8 or winding 9 is fed with electric current. Moreover, use is made of a battery 9|, an ammeter 92, a master switch 93, an electromagnet 94 or lower pitch relay, an electromagnet 95 or higher pitch relay, and condensers 96 and 91 for avoiding sparks at the terminals of rockers 98 and 99 actuated by the electromagnets 94 and 95. Moreover, the installation is controlled, generally speaking, by a four position controller I08 having two series of conducting blades NH and I82 mounted on the same shaft of the controller. Each series of conducting blades [0| or I02 has two blades arranged perpendicularly to each other. In the position A of the controller, as shown in Figure 1, in which the blade Ill I connects the contacts I05 and H2, while blade I02 connects the contacts I02 and I02, all the-circuits are open; it is the stoppage position. In the position B, the blade IM connects the contacts I04 and I05, and the blade 12 connects the contacts "12 and I20. In such a position of the controller I00, the blades of the alrscrew are caused to move towards the higher pitch position.- In the position C, the blade Ill connects the contacts I ll and 2 while blade I02 connects the contacts II. and I02". In such a position, the blades of the airscrew are caused to move towards thelower pitch position. In the position D. the blade Ill connects the contacts I04 and I I I, while the blade I02 connects the contacts and I20; in such a position of the controller I00 the control is automatically eflected by the regulator (Figure 2).

Position B of the controller 100 In this position, the closing of the following circult is obtained: positive pole of battery 0|, wire |0I ammeter 02, wire |02, wire I03, contact piece I04, blade IOI, contact piece I05, wire I00,

wire I01, field winding 0, motor -1, earth, wire I00, master switch 03, wire I00, negative pole of battery 0|. The motor rotates in the direction which causes the blades of the airscrew to be moved towards the higher pitch position.

Position C of thecontroller 100 In this position, the closing or the following circuit is obtained: positive pole of battery 0|,

wire I0I ammeter 02, wire I 02, wire I03, contact piece I04, wire IIO, contact piece III, blade IIII, contact piece 2, wire II4, wire II5, field windin; 0, motor 1, earth, wire I00, master switch 03, wire I00, negative pole of battery 0|. The motor rotates in the direction which causes the blades to be moved towards the lower pitch position. a

Position D of the controller 100 In this position, the operation is autonriatic and, accordingly as'the index I engages wlth contact I or contact 0, the blades move towards the lower pitch position or the higher pitch position.

when the index I engages with contact 5, the

closing of the iollowing circuit is obtained: positive pole of battery 0|, |0I ammeter 02, wire I02, wire IIO, contact piece IIO, blade I02, contact piece I20, wire I2I, wire I22, contact 00,"cont'act piece 00, contact 80, wire I23, brush I (Fig. 2), drum I, brush I wire 80, index I,

contact piece 5, wire 0|, brush drum 0*, brush 5*, wire I24, 'electromagnet 04, wire I25, wire I20, wire I21, wire I00, master switch 00, wire I00,

negative pole of'battery 0|. 7

The electromagnet 04 is energized and actuates the rocker 00 which closes the following circuit:

positive pole of battery 0|, wire I0I ammeter 02, wire I02, wire 0, contact piece II9, blade I02,

contact piece I20, wire I2I, wire I20, contacts I20, wire I30, wire I01, field winding 0, motor 1; earth, wire I00, masterswitch 03-, wire I00, negative pole of battery 0|. The motor rotates in the direction which causes the blades. of the airscrew to be moved towards the lower pitch position.

When the index I engages with contact 6, the

closing of the following circuit is eflected: positive pole of battery 0I, .wire I0| ammeter 02,

wire I02, wire 8, contact piece IIO, blade I02,-

contact piece I20, wire I2I, wire I22, contact 00, contact piece 88, contact 00, wire I23, wiper I drum I, wiper I wire 80, index I, contact 0, wire 02, wiper 6, drum 6", wiper 6, wire I33, electromagnet 05, wire I34, wire I26, wire I21, wire I08, master switch 03, wire I00, negative "pole of battery 0|.

The electromagnet 05 is energized and .actuates the rocker 00 which closes the following circuit: positive pole of the battery, wire I0I ammeter 02, wire I02,- wire 0, contact piece IIO,

bladeigi02, contact'piece I20, wire I2I, wire-I20,

installation in service conditions, or on the contact piece 200 for placing the blades of the airscrew in the winds eye position,athat is to say for placing the blades of the airscrew in planes substantially parallel to the longitudinal axis of theairplane. Moreover, in this modification, an intensity relay 20| for alamp and a lamp 202 are provided. Furthermore, the installation comprises a switch 203 and the collector rings, interposed between the flxed part of the installation and the motor 1 controlling the variations of the pitch of the airscrew, which motor is mounted on the hub of the airscrew, are diagrammatically indicated at 204 (circuit for the winds eye position), 205 (circuit of the small pitch), 206 (circuit oil the large pitch), 201 (common circuit).

The arm 200 of the primary controller being placed on the service contact piece 200', the blades IM and I02 of the controller I00 can be placed in the various positions A, B, C, and D.

Position A of controller 100 In this position, illustrated in Fig. 3, all the circuits are open, the installation is then in stoppage position) Position B of controller 100 In this position, the closing of the following circuit is obtained: positive pole ofthe battery 0|, wire I0|, contact piece I0", wire IOI relay 20I, wire IOI, ammeter 02, wire I02 arm 200 contact 200', wire I02 contact IIO, wire I03, contact I04, blades IOI, contact I05, wire I00, contact piece I06 wires I06 and 29I, ring 205, wire I01, contact breaker 208, wire 202, field winding 0, motor, 1, wire 220, ring 201, wire I00 contact piece I00, wire I08, master switch 03,

wire [00,contact piece I00'=, wire I00, negative pole of the battery 0|. The motor rotates in the direction causing displacement of the blades towards the higher pitch position.

It will be noted that the circuit of the operation signalling lamp 202 is closed between relay 20I and wire I00 through; wire 230, lamp 202- and wire 23L 1 Position 0 of controller 100 In this position, the closing of the following circuitis obtained: positive pole of the battery 0|, wire IOI, contact piece IOI wire IOI relay 20I, wire |0| ,.ammeter 02, wire I02 'arm 200 contact 200, wire I02, contact H9, wire I03, contact I04, wire IIO, contact III, blade IOI, contact II 2, wire, I I4, contact piece H4, wires |4 II4, ring 206, wire 232, contact breaker 2 I0, field winding 8, motor 1, wire 220, ring 201, wire I08", contact piece I00, wire I00, master switch 03,

- wire 100', contact I002 wire I00 negative pole of battery 0|. The motor-rotates in the direction causing displacement of the blades towards the lower pitch position.

As inthe position B, the circuit of the signalling lamp 202 is closed.

Position D of controller 100 In this position, the operation is automatic and, accordingly as the index I comes against contact 5, or contact 6, the blades move towards the higher pitch position, or towards the lower pitch position.

The contacts 258, 259 and 260, controlled by the armature of the electromagnet 94, as well as the contacts 258*, 259 and 260 controlled by the armature of the electromagnet 95 are normally open when the electromagnets are unenergized. On the contrary the contact 280, controlled by the armature of the electromagnet 284, is normally closed when the electromagnet 284 is unenergized.

When the index I comes against contact 5, the closing of the following circuit is obtained: positive pole of battery 9i, wire IOI, contact piece IOI wire IOI relay 20I, wire II ammeter 92, wire I02", arm 200 contact 200 wire I02, contact II9, blade I02, contact I20, wire I2I, contact piece I2I wire I2I wire 250, limit switch 203, contact 25I, wire 252, wire 253, index I of the regulator, contact 5, wire I24, wire 254, electromagnet 94, wires 255, I25, I25, I08 contact piece I08, master switch 93, wire I09, contact piece I09 wire I09 negative pole of battery 9|.

The electromagnet 94 is energized and actuates the contacts 258, 259, 260 for applying them against fixed contacts 25I, 262 and 263, respectively, this causing the closing of the following circuits:

(a) positive pole of battery 9|, wire I M, contact piece IOI wire IOI relay 20I, wire IOI ammeter 92, wire I02", arm 200 contact 200 wire I02, contact II9, blade I02, contact I20, wire I2I contact piece l2", wire 'I2I wire I2I, contacts 253 and 260, wire 290, wire 29I,

ring 205, wire I01, contact breaker 208, wire 292, field winding 9, motor 1, wire 220, ring 201, wire I08 contact piece I 08, master switch 93, wire I09*, contact piece I09, wire I09 negative pole of battery 9I. The motor rotates in the direction causing displacement of the blades towards the higher pitch position. The index I tends to move in the direction of the arrow F, by opening the initial circuit of electromagnet 94 at contact 5, but the following holding circuit has been closed:

(11) positive pole of battery 9|, wire IOI=, contact piece I0", wire IOI relay 20I, wire IOI ammeter 92, wire I02, arm 200, contact 200', wire I02, contact 9, blade I02, contact I20, wire I2I contact piece I2I wire I2I wire 250, limit switch 203, contact 25I, wire 252, wire 283, contacts 280 and 28I, wires 282, 300, pallet 259, contact 262, wires SM, 254, electromagnet 94, wires 255, I25, I26, I08", contact piece I08, master switch 93, wire I09, contact piece I 09*, wire I09 negative pole of battery 9|.

The electromagnet 94 is maintained energized until the contact index I comes opposite contact piece I2, this causing the closing of the following circuit:

(c) positive pole of battery 9|, wire IOI, contact piece I0", wire IOI relay 20I, wire I 0i, ammeter 92, wire I02 arm 200, contact 200, wire I02, contact II9, blade I02, contact I20, wire IZIP, contact piece I 2i", wire "I", wire 250, limit switch 203,*wire 252, wire 253, index I, contact piece l2, wire I23, electromagnet 284, wire 303, wire 304, contacts ZIB-and 28l, wire engaged with contact 6 for controlling the dis placement of the blades towards the lower pitch position, the circuits including in this case the electromagnets 95 and 284 and the contacts 280, 28I, on the one hand, and 258* and 259 260 and 26W, 262- and 263, on the other hand.

For moving the blades to the winds eye position, the arm 200 is placed on contact 200 and the following circuit is closed:

Positive pole of battery Si, wire IOI, contact piece I0", wire IOI relay 20I, wire IOI ammeter 92, wire I02 arm 200 contact piece 200, wire 35I, contact piece 352, wire 353, ring 204, wire 354, contact breaker 209, wire 355, field winding 9, motor 1, wire 200, ring 201, wire I08 contact piece I082 master switch 93, wire I09 contact piece I092 wire I09", negative pole of battery 9 I The limit switches 208-2092l0 are each of the well known type comprising a movable contact 208 209a2l0a actuated by a finger belonging to the slide-block-434 which will be described in reference to Figs. 4 and 5. The said limit-switches have for their object to break the circuit of the motor 1 when the blades of the airscrew have attained either the lowest or the highest pitch position, or the winds eye position.

What I claim as my invention and desire to secure by Letters Patent is:

In an electric motor control system, a source of electric energy having two terminals, an electric motor having two field circuits, each of said two field circuits corresponding to a diflerent direction of rotation of said motor, a receiving device, means for transmitting to the receiving device the rotary motion of the motor, a switch having two exterior fixed contacts and a central fixed contact, and a movable contact, arranged to cooperate with the three fixed contacts and connected to the first of the terminals of the source of electric energy, means responsive to the variations of position of the receiving device for displacing said movable contact, a first relay connected on the one hand to the second terminal of the source of electric energy and on the other hand to the first of the two exterior fixed contacts of the switch, a second relay connected on the one hand to the second terminal of the source of electric energy andon the other hand to the second of the two exterior fixed contacts of the switch, a holding circuit for each of said relays, a deenergizing circuit, each relay including a working contact arranged in the holding circuit thereof, a working contact arranged in the deenergizing circuit, a working contact also arranged in one of the two field circuits of the motor, and a third relay arranged in the deenergizing circuit and connected on the one hand to the second terminal of the source of electric energy and on the other hand to the central fixed man PAUL Rant. 

